Energy consumed by humankind is limited, and global warming caused by carbon dioxide generated by using energy is the greatest problem humankind faces in regards to the energy crisis. Accordingly, energy regulations of each country have been tightened day by day, and an energy rating system for home appliances is a permanent problem that manufacturers have. An energy rating system of a government which requires maximum efficiency while efficiently using less energy well accords with the needs of consumers who desire high internal capacity and low power consumption. Particularly, many studies on refrigerators have been performed for the past several decades, and studies for improving the efficiency of a cooling cycle, a compressor, a heat exchanger, and the like have reached their limit. Accordingly, recent studies on thermal loss are mainly performed, and many attempts to increase energy efficiency by strengthening insulation performance of refrigerators have been performed.
An insulating material such as an existing polyurethane has a heat conductivity of about 20 mk/m·K. When the insulating material is used, a thickness of an insulating wall of a refrigerator becomes greater so that storage capacity of the refrigerator is reduced. Accordingly, to solve these problems, it is necessary to use a vacuum insulation member having excellent insulation performance.
According thereto, an insulating wall of a refrigerator may be formed using a vacuum insulation member and a foam material including polyurethane. Here, an effective arrangement of the vacuum insulation member and the foam material in the insulating wall is an issue for increasing a storage capacity of the refrigerator while maintaining insulation performance and minimizing a thickness of the insulating wall.